THURSDAY, Sept. 16 (HealthDayNews) -- Forty percent of American women of childbearing age now get enough folic acid to help prevent birth defects, according to a new March of Dimes survey.

That's a record proportion of women, up from 32 percent in last year's survey. While it's still far from the majority of women, it's heartening progress, March of Dimes officials said.

"We're still only at 40 percent, but that's a lot better [than in past years]," said Dr. Siobhan Dolan, associate medical director for the organization. "That's a big jump. Eight percent is a big and very exciting jump."

For years, the March of Dimes, as well as the U.S. Centers for Disease Control and Prevention (news - web sites) and other organizations, have urged women who could become pregnant to be sure they get at least 400 micrograms of folic acid, the amount found in most multivitamins, every day to prevent birth defects.

Folic acid is sometimes called folate. It's a B vitamin found in some enriched foods, such as brans, rice and cereals, and in vitamins. If women get adequate amounts of folic acid before pregnancy, it can reduce the risk of giving birth to children with neural tube defects, such as spina bifida, a defect in the spine, or anencephaly, a brain defect, according to the CDC.

Every year in the United States, about 2,200 babies are born with neural tube defects, according to the March of Dimes.

The Gallup survey was conducted for the March of Dimes and funded through a grant from the CDC. The results appear in the Sept. 17 issue of Morbidity and Mortality Weekly Report, a CDC publication.

Pollsters asked a national sample of 2,012 women aged 18 to 45 about their vitamin use, why they did or didn't take folic acid, and about their awareness of the importance of folic acid to prevent birth defects, among other questions.

Seventy-seven percent of the women said they were aware of folic acid, compared to just 52 percent when the same survey was done in 1995. While 40 percent of women now take folic acid daily in the form of multivitamins, just 28 percent did in 1995 and 32 percent did in 2003.

"We had concerns that low-carb diets might put women in a position where they didn't benefit from fortification in the food supply," she said, referring to low-carb dieters' habit of cutting down on or eliminating breads and other carbohydrate-rich foods. But it appears that women on low-carb diets may have paid more attention to their folic acid needs. In the new survey, 49 percent of women who said they'd been on a low-carb diet in the past six months said they took a multivitamin every day with folic acid.

But, she added, more public awareness efforts are needed. "We still have quite a long way to go before the vast majority of women begin to take folic acid in preparation for pregnancy," Cullins said. Ideally, all women of childbearing age should take enough folic acid.

Women should increase their consumption of a variety of foods enriched with folate, she said.

Another option, Cullins said, would be to add folic acid to oral contraceptives, which at least one manufacturer is looking into. That way, if a woman got pregnant while on the pill -- which is unlikely but can happen she would have gotten enough folic acid, Cullins said. And a woman who is on the pill then goes off because she wants to get pregnant will "have a head start on adequate folate levels," she said.